The structure of plastic corrugated tubes, particularly double-walled tubes with a continuous smooth inner wall, and the apparatus required for manufacturing them are well known (see as disclosed in U.S. Pat. Nos. 3,677,676, 3,994,646, and 3,280,430).
From European patent application EP-OS No. 0 135 634 (corresponding to U.S. patent application Ser. No. 532,857), it is already known to integrally mold on sleeve couplers in order to prepare such plastic corrugated tubes. The fundamental problem in laying such tubes is the relatively wide tolerance in terms of the outer diameter of the circular rings. As a result, laying of such a tube, that is introducing one end of the tube into a sleeve coupler is either completely impossible or possible only at great expense for assembly, while in another instance an adequately firm seat of the end of the tube in the sleeve coupler is not assured.